As indicated in Patent Literature 1 (Japanese Unexamined Patent Application Publication No. 2012-233680), there is a heat exchanger that includes a plurality of flat pipes and a plurality of heat transfer fins having cutouts into which the flat pipes are inserted. In this heat exchanger, the flat pipes extend in a fin stacking direction intersecting an air flow direction. In addition, in this heat exchanger, the heat transfer fins are stacked in the fin stacking direction and each include a plurality of the cutouts into which the plurality of flat pipes are inserted, the cutouts extending from a leeward side toward a windward side in the air flow direction, a plurality of fin main parts each formed between the cutouts that are adjacent to each other, a fin windward part extending on the windward side of the plurality of cutouts in the air flow direction continuously with the plurality of fin main parts, and a fin collar part extending from a peripheral portion of each of the cutouts toward one side in the fin stacking direction. In other words, in each heat transfer fin of this heat exchanger, the cutouts into which the flat pipes are inserted are formed so as to extend from the leeward side toward the windward side in the air flow direction, and the fin windward part extending continuously with the plurality of fin main parts between the cutouts that are adjacent to each other is formed on the windward side of the cutouts in the air flow direction.
When the heat exchanger of Patent Literature 1 is used with the flat pipes arranged in an up-down direction in a state in which flat surfaces of the flat pipes are directed upward and downward, condensed water adhering to the heat transfer fins gathers at portions on the leeward side of the fin main parts in the air flow direction and drains by dripping down from leeward-side tip portions of the cutouts. Condensed water, however, drips from the leeward-side tip portions of the cutouts when the condensed water grows to a size that enables the condensed water to drip by its own weight. Accordingly, in such a condensed-water drainage structure, condensed water easily remains in spaces formed between the fin main parts adjacent to each other in the fin stacking direction on the upper side of fin collar upper portions, and it is thus difficult to obtain sufficient drainage performance.